[PATCH RFC 2/4] dev_dax_iomap: Temporary hacks due to linkage issues

["John Groves" <john@jagalactic.com>]

From: John Groves <john@groves.net>

These are functions that should be called from outside, but I had
linkage issues and did this hack instead. Will fix in the "real"
patches...
---
 drivers/dax/bus.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 1659b787b65f..1b55fd7aabaf 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1324,6 +1324,56 @@ static const struct device_type dev_dax_type = {
 	.groups = dax_attribute_groups,
 };
 
+#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP)
+
+/*
+ * This is write_pmem() from pmem.c
+ */
+static void write_dax(void *pmem_addr, struct page *page,
+		unsigned int off, unsigned int len)
+{
+	unsigned int chunk;
+	void *mem;
+
+	while (len) {
+		mem = kmap_atomic(page);
+		chunk = min_t(unsigned int, len, PAGE_SIZE - off);
+		memcpy_flushcache(pmem_addr, mem + off, chunk);
+		kunmap_atomic(mem);
+		len -= chunk;
+		off = 0;
+		page++;
+		pmem_addr += chunk;
+	}
+}
+
+/*
+ * This function is from drivers/dax/device.c
+ * For some reason EXPORT_SYMBOL(dax_pgoff_to_phys) didn't result in linkable code
+ */
+phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
+			      unsigned long size)
+{
+	int i;
+
+	for (i = 0; i < dev_dax->nr_range; i++) {
+		struct dev_dax_range *dax_range = &dev_dax->ranges[i];
+		struct range *range = &dax_range->range;
+		unsigned long long pgoff_end;
+		phys_addr_t phys;
+
+		pgoff_end = dax_range->pgoff + PHYS_PFN(range_len(range)) - 1;
+		if (pgoff < dax_range->pgoff || pgoff > pgoff_end)
+			continue;
+		phys = PFN_PHYS(pgoff - dax_range->pgoff) + range->start;
+		if (phys + size - 1 <= range->end)
+			return phys;
+		break;
+	}
+	return -1;
+}
+
+
 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
 {
 	struct dax_region *dax_region = data->dax_region;
-- 
2.40.1